Documented the -Werror=format compilation flag

Added compile-time format checking to C++17 NanoLog's example
GNUmakefiles and associated documentation. This helps users
avoid formatting errors that could corrupt the log file at
runtime (such as with issue #46) and closes issue #47.

README.md

@@ -63,7 +63,7 @@ The C++17 version of NanoLog works like a traditional library; just [``#include
 
 To build the C++17 NanoLog Runtime library, go in the [runtime directory](./runtime/) and invoke ```make```. This will produce ```./libNanoLog.a``` to against link your application and a ```./decompressor``` application that can be used to re-inflate the binary logs.
 
-When you compile your application, be sure to include the NanoLog header directory ([``-I ./runtime``](./runtime/)), and link against NanoLog, pthreads, and POSIX AIO (``-L ./runtime/ -lNanoLog -lrt -pthread``). Sample g++ invocations can be found in the [sample GNUmakefile](./sample/GNUmakefile).
+When you compile your application, be sure to include the NanoLog header directory ([``-I ./runtime``](./runtime/)), link against NanoLog, pthreads, and POSIX AIO (``-L ./runtime/ -lNanoLog -lrt -pthread``), and enable format checking in the compiler (e.g. passing in ``-Werror=format`` as a compilation flag). The latter step is incredibly important as format errors may silently corrupt the log file at runtime. Sample g++ invocations can be found in the [sample GNUmakefile](./sample/GNUmakefile).
 
 After you compile and run the application, the log file generated can then be passed to the ```./decompressor``` application to generate the full human-readable log file (instructions below).
 

benchmarks/GNUmakefile

@@ -35,7 +35,7 @@ USER_SRCS=Benchmark.cc
 ifeq ($(PREPROCESSOR_NANOLOG),yes)
 CXXFLAGS= -std=c++11 -DNDEBUG -O3 -g
 else
-CXXFLAGS= -std=c++17 -DNDEBUG -O3 -g
+CXXFLAGS= -Werror=format -std=c++17 -DNDEBUG -O3 -g
 endif
 CXX=g++
 

integrationTest/GNUmakefile

@@ -25,7 +25,7 @@ endif
 # Must be specified AFTER defining NANOLOG_DIR and USER_OBJ's
 include $(NANOLOG_DIR)/NanoLogMakeFrag
 
-CXXFLAGS= -std=c++17 -O3 $(CXXWARNS) -Werror
+CXXFLAGS= -Wformat -std=c++17 -O3 $(CXXWARNS) -Werror
 
 all: testApp basic_decompressor
 

sample/GNUmakefile

@@ -10,8 +10,10 @@
 #
 #####################################################################
 
-# -DNDEBUG and -O3 should always be passed for high performance
-CXXFLAGS= -std=c++17 -DNDEBUG -O3 -g
+# -Werror=format should _always_ be enabled to catch formatting errors
+# early during compilation rather than at decompression.
+# -DNDEBUG and -O3 are for high performance
+CXXFLAGS= -Werror=format -std=c++17 -DNDEBUG -O3 -g
 
 NANOLOG_RUNTIME_DIR=../runtime